English: US sailors launching a radiosonde at a military airport in 1943 during World War 2. The radiosonde consists of a battery-powered instrument package (white box) carried aloft with a helium-filled weather balloon. As it ascends it measures temperature, humidity, and air pressure and radios the information to a ground receiver. At an altitude of around 70,000 ft (23 km) the balloon pops, and the radiosonde floats back to earth suspended by the the red parachute visible on the support line. By WW2 the US Weather Bureau launched weather balloons daily from 80 sites around the US
This 1943 issue of Radio News magazine would have the copyright renewed in 1970. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1970 show no renewal entries for Radio News. Therefore the magazine's copyright was not renewed and it is in the public domain.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.